Xanthophylls are yellow pigments that form one of two major divisions of the carotenoid group. Their molecular structure is similar to carotenes, which form the other major carotenoid group division, but xanthophylls contain oxygen atoms, while carotenes are purely hydrocarbons with no oxygen. Xanthophylls contain their oxygen either as hydroxyl groups and/or as pairs of hydrogen atoms that are substituted by oxygen atoms acting as a bridge (epoxide).
Like other carotenoids, xanthophylls are found in highest quantity in the leaves and/or flowers of most green plants, where they act to modulate light energy. The xanthophylls found in the bodies of animals, and in dietary animal products, are ultimately derived from plant sources in the diet. For example, the yellow color of chicken egg yolks, fat, and skin comes from ingested xanthophylls (primarily lutein, which is often added to chicken feed for this purpose).
The yellow color of the human macula lutea in the retina of the eye comes from the lutein and zeaxanthin it contains, both xanthophylls again requiring an exogenous source in the human diet to be present in the eye. These function in eye protection from ionizing blue light, which they absorb.
The group of xanthophylls includes (among many other compounds) lutein, zeaxanthin, neoxanthin, violaxanthin, and α- and β-cryptoxanthin.
There is an interest in developing products that have high levels of xanthophylls. For example, xanthophylls are known to have antioxidant properties and have been shown to prevent age-related macular degeneration (AMD).
Marigold flowers are the most commercially significant source of xanthophylls. A prominent supplier of xanthophyll pigments extracts them from a commercial marigold hybrid (Hybrid 50011, U.S. Pat. No. 6,894,208) which typically has a total xanthophyll composition of 94% lutein (L) and 6% zeaxanthin (Z); with an average L:Z ratio range of 15:1. Marigold hybrids that produce zeaxanthin as the primary xanthophyll, with minimal lutein, would provide an agronomically feasible source of zeaxanthin for the human dietary supplement industry. Chrysantis, Inc. (West Chicago, Ill.) has developed a high zeaxanthin marigold hybrid via mutagenesis.